Regulation of androgen receptor mRNA and protein in the rat testis by testosterone

__Abstract__ Adult rats were treated with ethane dimethane sulphonate (EDS), an agent that destroys Leydig cells. Within 5 days after EDS treatment, the levels of testosterone (T) in the circulation and in the testis were decreased to very low values, which makes it possible to manipulate the testicular T concentration through administration of exogenous T. Spermatogenesis was not markedly affected within 5 days after EDS treatment, also not in the absence of T administration. In testes of EDS-treated rats, the androgen receptor mRNA (ARmRNA) level remained unaltered for 5 days. In ventral prostate, however, this treatment caused a pronounced upregulation of the level of ARmRNA, which could be counteracted by implantation of silastic T implants immediately after EDS treatment. In EDS-treated rats carrying a T implant and in untreated rats, the same number of specific [3H]R1881 binding sites was observed using a total testis nuclear fraction (Scatchard analysis). In testes from EDS-treated rats without T implants, androgen receptors (AR) did not fractionate into the nuclear fraction; however, the total testicular AR content in these animals (measured by nuclear [3H]R1881 binding after receptor transformation through injection of a high dose of T, 2 h before killing the rats) remained unaltered. Immunoprecipitation and Western blotting using anti N-terminal antibodies seemed to indicate that the total testicular amount of AR protein in the EDS-treated rats was very low as compared to that in EDS-treated rats carrying T implants and in untreated rats. Even after receptor retransformation (by injection of a high dose of T) the receptors were not quantitatively detected by immunoprecipitation and Western blotting. This may point to a structural modification of the AR that occurs in the prolonged absence of androgens

Quantitative analysis of spermatogenesis and apoptosis in the common marmoset (Callithrix jacchus) reveals high spermatogonial turnover and spermatogenic efficiency.

Spermatogenesis is characterized by the succession in time and space of specific germ cell associations (stages). There can be a single stage (e.g., rodents and some macaques) or more than one stage (e.g., chimpanzee and human) per tubular cross section. We analyzed the organization of the seminiferous epithelium and quantified testicular germ cell production and apoptosis in a New World primate, the common marmoset (Callithrix jacchus). Tubule cross sections contained more than one stage, and the human six-stage system could be applied to marmoset spermatogenesis. Stereological (optical disector) analysis (n = 5) revealed high spermatogenic efficiency during meiosis and no loss of spermatids during spermiogenesis. The conversion of type A to type B spermatogonia was several-fold higher than that reported for other primates. Highest apoptotic rates were found for S-phase cells (20%) and 4C cells (15%) by flow cytometric analysis (n = 6 animals); histological analysis confirmed spermatogonial apoptosis. Haploid germ cell apoptosis was <2%. Marmoset spermatogenesis is very efficient and involves substantial spermatogonial proliferation. The prime determinants of germ cell production in primates appear to be proliferation and survival of spermatogonia rather than the efficiency of meiotic divisions. Based on the organizational similarities, common marmosets could provide a new animal model for experimental studies of human spermatogenesis